The Roar of the Bay

The Roar of the Bay
The Roar of the Bay

Sunday, April 7, 2013

Red Rocks / McGahey Brook (Cape Chignecto - Advocate Harbour)

I've been catching up on a lot of past trips I made in the Maritimes that I didn't have time to post on my blog. One such trip was a rockhunting trek in Nova Scotia in the Advocate Harbour area, West of Parrsboro.

Site (circled in red), Isle Haute (bottom left)

The topography of the southern Chignecto region is very faulted, showcasing the collision of this part of the continent with North Africa some 400 million years ago, forming the ancient Supercontinent Pangaea. The Carboniferous strata of this regions has been folded and faulted in spectacular fashion, neighboring Jurassic (Early) age basalts from North Mountain, which you can see at Cape d'Or and other locations along the Minas Basin, and rhyolites in the West (ie. Spicer's Cove). Cape d'Or is especially known for its natural copper deposits, once mined in the early 1900s.

1- Actual Location (C-H Carboniferous, Early - Horton Group)
CC - Carboniferous, Late - Cumberland Group (ie. Joggins)
2- Cape d'Or, Copper deposits, basalt lava flows, major fault
3- Jurassic, Early - North Mountain basalts (various overlapping lava flows)

Isle Haute, composed mainly of basalt (Jurassic)

Since the last ice age about 11,000 years ago, the area was uplifted. The land rebounded, leaving raised beaches on top of the cliffs with layers of glacial till.

Because the region was involved in this tectonic tug of war, whatever fossils found in the rock has been worked mostly beyond recognition. There are some rare fossils that escaped this calamity, but they are very scarce indeed. Sandstone and other types of sedimentary rock had been metamorphosed, pulled apart and pressed, warped, and molded.

Beading, sandstone under tectonic stress

Tremendous pressure applied to these rocks introduced minerals such as quartz (quartzite). The shales and mudstone are practically pulverized, ground into a very fine material, resulting in this dark sand all over this beach.

Glacial striation or fault scarring?

Horsetail (related to ancient club mosses, lycopsids)

Nice folding!

Folding and faulting

Sedimentary strata changed under incredible stress

Morphology drastically being modified in several episodes

This area is very fascinating and exciting. Here is a place where you can witness the continent being pushed around and shaped over and over during a very long period of time, in various ways, due to harsh and extreme forces exerted by the tectonic activity at the time of continental push and separation over 400 million years. The scale of it is amazing on the grandiose scale to the micro level of change. This shows that rocks can be very malleable under great stress. What doesn't bend, eventually breaks.


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